I think that lot of these issues raised here will be non-issues when there is a good alternative to gasoline. Then noboby will want to use polluting gasoline engines anymore. That alternative is not here yet, but I bet the situation is totally different after half a year.

So what will happen in the next half a year? There will be validation for the Rossi E-Cat that will wipe out all current polluting engines. When your engine will need fresh supply of energy only every half a year, consisting of less than pound of nickel plus some catalyst, there will be no needs for trade offs in automobile materials. You just manufacture the car with large enough powerplant to handle the average demand and some batteries to cover up the surge needs. Yes, this implies series hybrid layout with E-Cat + generator + battery + electric motor. The breaktrough here is that you can keep the E-Cat on always, if desired, and charge the battery. If you need to turn E-Cat off, because battery is full, battery energy is used to restart E-Cat when one resumes driving or when battery status is low enough to warrant recharge. And with fuel expenses in 100-1000 USD range twice a year, with no pollution, the big losers will be the big energy industry, including oil giants and your electricity supplier too, because of course you will use a separate E-Cat for powering and warming your house too.

Alex, you listed a number of paths to better MPG. Each may be a chip at the challenge. The path to 54.5 may be in the goal itself. The moonshot had fewer years than this goal. There's power in goals. Without a goal, we experence the drift was saw in MPG from the late 80s to the early 2000s. There's nothing like a goal -- fueled by good old-fashioned competition -- to get where you need to go.

Materials: This will be the biggest factor. Lighter weight materials will cost more and have the best effect on fuel economy. So lets weight this factor at 25% of the total improvement.

Form Factor: I am not sure how this is factored in. The car maker fleet is the total vehicles sold and is a mix of models. People kept buying SUV's because they liked them. So the automakers fleet was weighted more toward lower mpg vehicles. Presumably the automakers will be required to adjust prices downward on higher mileage vehicles to improve sales. As to the point on form factor, I would like to buy an inexpensive but nice high mileage commuter type vehicle. I can keep another vehicle for other purposes. I will weight this factor at 15%.

Powertrains: Advanced automatics will help. Perhaps a CVT to enable optimum engine operations and load. An engine driven Permanent Magnet Generator (PMG) and batter pack might be a serious contender. The engine can operate at optimum fuel efficiency while the pmg is managed to control the load. In the case of most diesels and gas turbines there is an optimum speed and the load on the engine determines the fuel consumption. This is already in trials in the case of some turbine driven pmg equipped buses. In fact they used 2 30 KW gensets. I would weight this factor at 25%.

Tires: I am not sure how much the rolling resistance of the tires affects gas mileage but I have heard of new solid rubber tires with flexible spokes in the wheel that probably improve this factor by maybe 50% or so. In any case I am not sure if Nitrogen really helps. I weight this factor pretty low at 10%.

Fuel: If the standard is based entirely on a "gallon" then energy density of the fuel is the factor to consider. I recall a special fuel used for cruise missiles which was a special formulation for very high energy content. I don't see anything but diesel, gasoline and natural gas (methane) being used commercially. Ethanol variants are less dense energy wise. It might be that some kind of higher energy density gasoline, maybe named HM premium (high mileage) premium with a better octane rating emerges. I weight this factor at 10%.

IVHS: This is a good factor to consider and and might help make driving more efficient by eliminating or reducing driver input. I strongly believe that electric cars will be 50% of the cars on the road in a decade. They will also be controlled by computers to reduce inefficient driver inputs. The road will help but making the roads intelligent enough will cost a lot. This factor I give 15%.

Per the post regarding the E-Cat, I will believe it when there is a repeatable design produced and verification of the process. A demonstration even though monitored by witnesses is insufficient. The device needs to be disassembled and analyzed by engineers. If it is indeed cold fusion then lots of problems will be solved. I find cold fusion a difficult technology to base the future on.

I was wondering the same thing about the tires, Ivan. It seems to me that a solid composite would maximize the mpg, rather than a nitrogen fill. Of course that would probably wreck the smoothness of your ride, so we would end up have to add "suspension" to Alex's list.

I know you didn't want to focus on the proposal, Alex, but to me, it begs the question: Does the 1.7 MPG reduction really change things that much in terms of automakers' ability to meet the stated goals in the stated timeframe?

I think getting the weight down will continue as the industry pursues more cost effective carbon fiber assemblies and aluminum/composite engine component technologies. I don't want to be in a Smart Car when the person driving their large SUV while talking on the phone doesn't apply their brakes in time for the traffic light that I'm stopped at.

I can see the morphing-shape car coming into vogue for the efficient high speed highway cruising. I'm a big fan of the BMW concept car with the morphing skin. You can see here if you haven't seen it- http://www.youtube.com/watch?v=OKRSzzSWF6U Maybe the flexible material can stiffen up for impact preparedness when a current is run through it (ala Batman's foldable wing technology!).

This whole 50 some mpg brings to light on of the most frustrating parts of the whole gas mileage target bills and such. What does it really mean to a consumer. Is the consumer really going to see a 54 mpg car. Or is that only going down hill with the wind behind his back on the highway? And according to what I heard on the news is the manufacturers who are targeting these mileages won't really be getting to these targets because they get incentives for making other changes to this or that and so the real target they will achieve will be much less...more like 45 or so.

I think one of the biggest things we can do to help encourage developement is to gain some credibility by stating clearly how the gas mileage is calculated. As a consumer I really don't believe the mpg on the windshield of any car. So how can I get excited when a program like this comes out. As an engineer there is nothing more frustrating than not have a clear, simple specification that I can meet.

And has been discussed in other posts, how do you calculate true gas mileage if it takes X number of KWhrs in order to get the 54 mpg?

Gas mileage depends on many factors. Many of them are variables (or unknown) like passenger weights, pull loads, fuel mixture contents, environmental factors like temperatures, wind velocity, driving habits, etc. and of course mechaniical efficiency of the power train itself. I believe, it is OK to determine a range under certain conditions rather than a precise number of KWhrs to get to the 54.5 mpg?

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